A cliff-former is a geological unit of bedrock that is more resistant to erosion than overlying or underlying strata and consequently produces outcrops with high slope angles. It is more or less equivalent to ridge-former, and may be contrasted with slope-former. In humid environments, sandstones are typically cliff-formers. In arid environments, limestones are often cliff-formers also. Recent lavas may be cliff-formers as well.
In the Ridge-and-Valley Appalachians of the eastern United States the major ridge-formers are the Tuscarora, Pocono, and Pottsville Formations. [1]
Tamaqua is a borough in eastern Schuylkill County in the Coal Region of Pennsylvania, United States. It had a population of 6,934 as of the 2020 U.S. census.
The Cumberland Plateau is the southern part of the Appalachian Plateau in the Appalachian Mountains of the United States. It includes much of eastern Kentucky and Tennessee, and portions of northern Alabama and northwest Georgia. The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the dissected plateau lands lying west of the main Appalachian Mountains. The terms stem from historical usage rather than geological difference, so there is no strict dividing line between the two. Two major rivers share the names of the plateaus, with the Allegheny River rising in the Allegheny Plateau and the Cumberland River rising in the Cumberland Plateau in Harlan County, Kentucky.
The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia, USA. The Allegheny Front forms the boundary between the Ridge-and-Valley Appalachians to its east and the Appalachian Plateau to its west. The Front is closely associated with the Appalachian Mountains' Eastern Continental Divide, which in this area divides the waters of the Ohio/Mississippi river system, flowing to the Gulf of Mexico, from rivers flowing into Chesapeake Bay and from there into the Atlantic Ocean.
The Shawangunk Ridge, also known as the Shawangunk Mountains or The Gunks, is a ridge of bedrock in Ulster County, Sullivan County and Orange County in the state of New York, extending from the northernmost point of the border with New Jersey to the Catskills. The Shawangunk Ridge is a continuation of the long, easternmost section of the Appalachian Mountains; the ridge is known as Kittatinny Mountain in New Jersey, and as Blue Mountain as it continues through Pennsylvania. This ridge constitutes the western border of the Great Appalachian Valley.
Sideling Hill, also Side Long Hill, is a long, steep, narrow mountain ridge in the Ridge-and-Valley physiographic province of the Appalachian Mountains, located in Washington County in western Maryland and adjacent West Virginia and Pennsylvania, USA. The highest point on the ridge is Fisher Point, at 2,310 feet (700 m) in Fulton County, Pennsylvania.
Massanutten Mountain is a synclinal ridge in the Ridge-and-Valley Appalachians, located in the U.S. state of Virginia. It is near the West Virginia state line.
The Potomac Highlands of West Virginia centers on five West Virginian counties in the upper Potomac River watershed in the western portion of the state's Eastern Panhandle, bordering Maryland and Virginia. Because of geographical proximity, similar topography and landscapes, and shared culture and history, the Potomac Highlands region also includes Pocahontas, Randolph, and Tucker counties, even though they are in the Monongahela River or New River watersheds and not that of the Potomac River.
Bald Eagle Mountain – once known locally as Muncy Mountain – is a stratigraphic ridge in the Ridge-and-Valley Appalachians of central Pennsylvania, United States, running east of the Allegheny Front and northwest of Mount Nittany. It lies along the southeast side of Bald Eagle Creek and south of the West Branch Susquehanna River, and is the westernmost ridge in its section of the Ridge-and-Valley Appalachians. The ridge line separates the West Branch Susquehanna Valley from the Nippenose and White Deer Hole valleys, and Bald Eagle Valley from Nittany Valley.
North Fork Mountain is a quartzite-capped mountain ridge in the Ridge and Valley physiographic province of the Allegheny Mountains, also known as the High Alleghenies or Potomac Highlands, of eastern West Virginia. Kile Knob, at 4,588 feet, is the mountain's highest point, and Panther Knob and Pike Knob are nearly as high.
Tuscarora Mountain is a mountain ridge of the Appalachian Mountains in the Ridge and Valley province in central Pennsylvania. It reaches its highest point on Big Mountain (Pennsylvania) at 2,458 feet (749 m) above sea level. The mountain is named after the Tuscarora people.
Brush Mountain is a stratigraphic ridge in the Appalachian Mountains of central Pennsylvania, United States, lying east of the Allegheny Front and west of Tussey Mountain. It runs along the southeast side of the Little Juniata River and forms a horseshoe around Sinking Run, and is the westernmost ridge in its section of the Ridge-and-valley Appalachians. The western ridge line separates the Logan Valley from the Sinking Valley.
Wills Mountain is a quartzite-capped ridge in the Ridge and Valley physiographic province of the Appalachian Mountains in Pennsylvania and Maryland, United States, extending from near Bedford, Pennsylvania, to near Cumberland, Maryland. It is the northernmost of several mountain ridges included within the Wills Mountain Anticline.
Tussey Mountain is a stratigraphic ridge in central Pennsylvania, United States, trending east of the Bald Eagle, Brush, Dunning and Evitts Mountain ridges. Its southern foot just crosses the Mason–Dixon line near Flintstone, Maryland, running north 130 km (80 mi) to the Seven Mountains of central Pennsylvania, near Tusseyville, making it one of the longest named ridges in this section of the Ridge-and-valley Appalachians. The ridge line separates Morrison Cove from the Woodcock Valley and Friends Cove from the Black Valley. Tussey Mountain lies in, and the ridge line forms parts of the borders of, Centre, Blair, Bedford and Huntingdon counties.
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, the include: the Atlantic Plain Province province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachain Province, and the Central Lowlands Province.
The Silurian Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia, USA.
The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania, West Virginia, Virginia, Tennessee, and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.
For other "River Knobs", see River Knobs (disambiguation).
The Devonian Mahantango Formation is a mapped bedrock unit in Pennsylvania, West Virginia, and Maryland. It is named for the North branch of the Mahantango Creek in Perry and Juniata counties in Pennsylvania. It is a member of the Hamilton Group, along with the underlying the Marcellus Formation Shale. South of Tuscarora Mountain in south central Pennsylvania, the lower members of this unit were also mapped as the Montebello Formation. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database.
The Mississippian Pocono Formation is a mapped bedrock unit in Pennsylvania, Maryland, and West Virginia, in the United States. It is also known as the Pocono Group in Maryland and West Virginia, and the upper part of the Pocono Formation is sometimes called the Burgoon Formation or Burgoon Sandstone in Pennsylvania. The Pocono is a major ridge-former In the Ridge-and-Valley Appalachians of the eastern United States
The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, Ohio, and Alabama. It is a major ridge-former in the Ridge-and-Valley Appalachians of the eastern United States. The Pottsville Formation is conspicuous at many sites along the Allegheny Front, the eastern escarpment of the Allegheny or Appalachian Plateau.
The major ridge makers are the Tuscarora (T), Pocono (Po), and Pottsville (Pt) Formations.